We demonstrate the spontaneous In-whisker formation from combinatorially sputtered YIn₃ thin films. The morphology and extrusion kinetics of In-whiskers are affected by the local chemical composition. In-whiskers are extruded from the film surface upon exposure to atmosphere, but not in vacuum. Consequently, In-whisker growth is accompanied by an increase in oxygen content in the films. The results presented enable controlled processing of 1-D submicrometer/nanostructured materials with respect to morphology and growth kinetics.